Coherent bulky yarn and process for its production



y 1966 A. 1.. BREEN ETAL 3,251,181

COHERENT BULKY YARN AND PROCESS FOR ITS PRODUCTION Filed July 9, 1964 2 Sheets-Sheet l F l G. 2.

TO WINDUP INVENTORS ALVIN L. BREEN HERBERT G. LAUTERBACH BY 72% M ATTORNEY y 7, 1966 A. L. BREEN ETAL 3,251,131

COHERENT BULKY YARN AND PROCESS FOR ITS PRODUCTION Filed July 9, 1964 2 SheetsSheet 2 F l G. 5

I 55 k \QI IIITI III...--. 57 I"""" I V 59 V am lmm F I G- 6 INVENTORS ALVIN L. BREEN HERBERT G. LAUTERBACH ATTORNEY United States Patent 3,251,181 COHERENT BULKY YARN AND PROCESS FOR ITS PRODUCTION Alvin Leonard Breen and Herbert George Lauterbach, Wilmington, DeL, assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed July 9, 1964, Ser. No. 381,465 3 Claims. (Cl. 57140) The present application is a continuation-in-part of our copending application Serial No. 698,103, filed November 22, 1957, which is relied upon to supplement the present disclosur This invention relates to a process for imparting crimp to amultifilament strand, such as a yarn or tow of synthetic linear polymer filaments, by treatment with a jet of hot compressible fluid, and to coherent bulky products having a novel crimped filament structure. The invention is more particularly concerned with the production of bulky yarn which provides a desirable dry, cotton-like hand when formed into fabrics.

Our prior application discloses and claims a general procedure for imparting crimp to a multifilament strand of plasticizable synthetic linear polymer filaments by feeding the strand through a turbulent plasticizing stream of a compressible fiuid having a temperature of at least 300 F. (at least about 149 C.) in which the individual filaments, while in a plastic state and under substantially Zero tension, are separated from each other and crimped into a random, three-dimensional, curvilinear, extensible configuration, then setting the crimp and taking up the strand at a rate which provides at least 30% overfeed to the turbulent stream. Bulky yarn produced in this way is characterized by the crimped configuration of the filaments, which is distinct from the crimp obtained by other processes such as mechanical crimping, and may also be distinguished by random alternating twist present in individual filaments. As more fully disclosed in our copending application Serial No. 287,464, filed June 6, 1963, now Patent No. 3,186,155, individual filaments possess alternate S and Z twist sections throughout their lengths, have a random number of turns between twist reversals, have a random continuously varying angle of twist along their lengths, have a random number of twist reversals per inch, and have at least one S turn and at least one Z turn per inch which have a twist angle averaging at least As commonly practiced, the bulky yarn of the above process is actually too soft, too loose and two voluminous for some applications. This is particularly true for textile uses when the yarn filaments are of 1 to IOdenier. Also, under certain processing conditions, the yarn exhibits a tendency to balloon out and cause processing difficulties.

The present invention makes available a novel bulky yarn having a close, well-defined, coherent filament bundle. In accordance with a preferred embodiment, the bulky yarn provides a desirable dry, cotton-like hand when formed into fabrics. Other objects and advantages of the invention will become apparent from the following disclosure and claims.

The products of the present invention may be characterized as multifilarnent strands, and fabrics prepared therefrom, of synthetic linear polymer filaments crimped in a persistent, random, three-dimensional, non-helical, curvilinear, extensible configuration, and having sufficient interfilament fusion to provide a coherent bulky filament bundle. Preferably, there are an average of 0.1 to interfilament fusions per 100 filaments, as determined at random cross sections along the strand. Pairs of filaments are fused together at random intervals along the strand, resulting in a coherency analogous to that of the inter- 3,251,181 Patented May 17, 1966 laced bulky yarn produced as illustrated in Examples XX and XXI of our application Serial No. 287,464, now Patent No. 3,186,155. Filaments also have the random alternating twist described in that application.

The above products of this invention are produced, in accordance with the general procedure of feeding a multifilament strand of plasticizable synthetic linear polymer filaments through a turbulent plasticizing stream of a compressible fluid having a temperature of at least C. in which the individual filaments are separated from each other and crimped while in a plastic state under substantially zero tension, by feeding the strand through the turbulent stream of compressible fluid at a temperature greater than the interfilament stick temperature of the filaments to cause fusion between filaments during the crimping treatment. Preferably, the temperature of the turbulent fluid is above the melting point of the filaments and the strand is fed through the fluid at sufficient speed to avoid excessive heating of the yarn, so that filaments do not melt or fuse together to an undesirable extent.

The invention will be more fully understood by reference to the drawings in which,

FIGURE 1 is a schematic perspective view of apparatus suitable for the production 'of the bulky yarn of this invention;

FIGURE 2 is an axial cross-sectional view of one form of jet device useful for the production of the bulky yarn;

FIGURE 3 is an axial cross-sectional view of a modified jet device useful for producing the yarn;

FIGURE 4 is an axial cross-sectional view of another form of jet device useful for producing the yarn;

FIGURE 5 is an axial cross-sectional View of a jet device useful for processing a tow of filaments or of a plurality of yarns;

FIGURE 6 is a greatly magnified cross-sectional view of a yarn of the present invention;

FIGURE 7 is a longitudinal view of a portion of a multifilament yarn, enlarged to illustrate the filamentary structure, and

FIGURE 8 is a longitudinal view along a pair of filaments isolated from a yarn and shown at a considerably enlarged scale to illustrate filament configuration and fusion.

In FIGURE 1, the moving supply yarn 10 passes through guide 11 to a pair of driven feed rolls 12, 13, makes several wraps around the rolls and passes once about draw pin 14.. The yarn continues onward to a pair of draw rolls 15, 16, which are driven at a higher speed than the feed rolls to draw the yarn. The yarn makes several wraps about the draw rolls, then travels onward through guides 17 and 18 to yarn passageway 19 of jet device 20. The yarn passes axially through the jet device, and hot air or steam is introduced through fluid passageway 21 from a suitable source (not shown) to crimp the yarn filaments. The hot filuid is supplied at a temperature greater than the interfilament stick temperature which is sufficient to produce filament fusion without actually melting the filaments. The hot fluid exhausts with the yarn against a screen-surfaced drum 22. The drum rotates to carry the yarn in 1a tensionless state away from the fluid stream, and the yarn cools sufiiciently to set the crimp. The bulky yarn passes from the drum through a guide 23 to a pair of driven take-up rolls 24, 25, which rotate at a slower speed than draw rolls 15, 16 to provide at least 30% overfeed. to the jet device. The yarn proceeds to a conventional windup or other treatment.

Yarn slippage upon take-up, when encountered, is readily controlled by employing a rubber-covered takeup roll cooperating at the nip with a rubber-covered cot roll.

FIGURE 2 illustrates a suitable form of jet device 20. The yarn passageway 19 has three sections: opening 30 to receive the yarn, restricted passage 31, and a treatment chamber 32 through which the yarn passes to exit orifice 33. Hot fluid, supplied through passageway 21, passes into the treatment chamber by way of channel 34 that intersects the yarn passageway 19 at a forward angle near the beginning of the treatment chamber.

FIGURE 3 illustrates a modification which includes a preheating chamber 35 in the yarn passageway, located between restricted passage 31 and the treatment chamber 32. The hot fluid is introduced from supply passageway 36 through channel 37, which intersects the yarn passageway at a forward angle near the beginning of preheating chamber 35, and also through channel 38, which intersects the yarn passageway at the beginning of the treating chamber as in the jet device of FIGURE 2. The operation of the two jet devices is the same except that preheating the yarn in chamber 35 facilitates treatment to impart the desired combination of crimp and interfilament fusion. The extent of preheating can be increased by increasing the length of chamber 35 or by heating the chamber with auxiliary means, such as an electrical heating element.

FIGURE 4 illustrates a jet device in which the yarn is introduced into the treatment chamber at an angle and the fluid passageway is aligned with the axis of the treatment chamber. This device consists of a body member 49, an orifice member 41 held in place by clamp 42 and screw 43, and a yarn-tube member 44 supporting a hollow needle 45. Fluid is introduced through passageway 46 directly into the entrance end of treatment chamber :7. The yarn enters the chamber through needle 45 at a forward angle near the entrance end. The exit end of the needle has a cutaway section giving a lip 48 which is supported in hole 49 in orifice member 41. The yarntube member 44 is supported in the body member in an adjustable fashion by a screw tightened in tapped hole 50.

FIGURE illustrates a jet device suitable for treating a tow of filaments or of a plurality of yarns. This consists of a hollow body member 51, a tow guide member 52 secured to the body by screws 53, and an orifice member 54 secured to the body by screws 55. The fiuid enters the body member through opening 56, the tow enters through passageway 57, and both enter the treatment chamber 58 at the entrance end. The tow passageway and the treatment chamber have slot-shaped cross sections, so that the tow passes through the device in the form of a flattened ribbon. The tow and treatment fluid are impinged against a screen-surfaced drum 59 which carries the tow away from the fluid in a tensionless state to set the crimp.

The turbulent stream of compressible fluid used in producing the products of this invention may be hot air, steam, or any other gas or vapor capable of plasticizing the filaments provided that it has a temperature of at least 150 C. sutfiicent to maintain the surfaces of the filaments at a temperature greater than the interfilament stick temperature during treatment. The temperature of the fluid must be regulated so that the filaments do not melt. However, the most effective bulking and the greatest productivity is obtained when the temperature of the turbulent fluid is above the melting point of the filament material. Preferably, pairs of filaments are joined with a common, molten mass of polymer at random intervals during the treatment. The temperature and pressure of the fluid, the yarn speed and the length of the treatment chamber are adjusted so that the filaments contact one another at the desired frequency and fuse together without excessive heating of the strand, and the filaments then cool quickly below the fusion temperature of the polymer to retain interfilament fusions. Care must be taken to avoid excessive heating of the strand since this tends to produce a fused product with reduced bulk and undesirable harshness or, in severe cases, a strand no longer useful in normal textile applications.

The temperature of the heating fluid must be high enough so that either alone or in combination with some auxiliary plasticizing component, e.g., water, acetone or other solvent, it will soften or plasticize the filamentary material passing through the heating area. The optimum temperature, of course, varies depending upon the material being treated, the form of the material being treated; i.e., staple or continuous filament, the denier or yarn size, the rate of throughput, the degree of turbulence and/or pressure of the treating fluid, the design of the treating chamber, and the degree of crimping desired. The temperature can range as high as 700 F. or more and a preferred range is 500.600 F. (260315.5 C.). The controlling factors are the characteristics of the material being treated and the temperature actually reached by the filamentary material during treatment. The yarn temperature during the crimping operation should exceed the second order transition temperature to insure permanence of crimp. The true upper limit, of course, is the temperature at which objectionable melting and/or chemical degradation of a given yarn takes place.

Multifilament strands having the desired degree of crimping and interfilament fusion can be prepared in accordance with this invention from filaments having a round cross section, or the cross section may be trilobal, cruciform, Y-shaped, or of any other conventional shape. The filaments may be composed of any plasticizable synthetic linear polymer, such as the thermoplastic linear condensation polyesters or polyamides. Excess finish on the filaments, especially finish containing caustic, reduces effective interfilament contact and is a negative factor for producing the desired interfilament fusion. It is preferred that a feed yarn contain little or no twist. The twist level should be below 2 turns per inch and preferably below 1 t.p.i.

The process is well adapted for using a number of ends of yarn in the same jet. Thus, it is possible to pass two to five or more ends through a single jet at the same time. The resulting yarn may have the ends well blended or it may have bulked ends which will be distinctly separate and independently windable depending on the processing conditions. Two or more yarns may also be treated using different tensions or feed rates so as to produce a tension stable bulky yarn with extensibility confined to that of the shorter member. Likewise, two different types of yarn such as nylon and rayon may be passed through the jet. The differential shrinkage and heat-setting of the two types of yarn provides many interesting effects which are desirable for esthetic reasons in textile materials. The crimp of the product is extremely stable and is not removed by tensions up to the breaking load.

The products of this invention assume a three-dimensional, non-helical, random, curvilinear configuration. This structure is different from the bulked materials prepared by the various twist-setting operations, since these have predominantly a helical and regular type of filamentary deformation. It is different also fromthose prepared by the well-known stutter box technique, since the latter are characterized by a regular and reversing or sawtooth planar type of crimp. Because of the turbulent and random fluid currents in the treating chamber of the subject process, the crimp in the subject products is threedimensional and random in crimp amplitude and period. The high degree of turbulence in a confined space results in a very high crimp level, and a curvilinear rather than rectilinear, saw-tooth, helical or crunodal loop type of filamentary configuration. The crimp is permanent to normal fiber processing conditions and will persist in filaments taken from the yarn bundle. On exposure to hot water, marked increases in crimp amplitude and frequency are obtained. The useful products of this invention have a crimp level in excess of 5 per inch, and preferably above 10 per inch. They may even be as high as 70 or crimps per inch.

The products have sufiicient interfilament fusion to provide a novel, coherent bulky filament bundle. The close, well-defined filament bundle facilitates processing of yarns into fabric. A relatively high frequency of interfilament fusion results in fabric having a harsh hand, which may be desirable for some purposes. Preferably, the incidence of interfilament fusion is from 0.1 to 10. fusions per 100 filaments, as determined at random crosssections along the yarn, since this provides fabric having an appealing dry, cotton-like hand which is nevertheless soft in comparison with unbulked yarn or bulked yarn having greater interfilament fusion. The yarn yields fabrics of excellent uniformity in weave pattern or stitch formation. It not only processes better than similarly bulked yarn which lacks interfilament fusion; it also leads to fabrics which are bulkier than fabrics made from such yarn (without interfilament fusion), even though the latter is more voluminous in yarn form.

FIGURE 6 illustrates the appearance of a magnified cross section of a trilobal filament yarn of this invention. The trilobal cross section is seen in filaments 60. One form of interfilament fusion is shown between filaments 61 and 62. A line 63 has been drawn to show where fusion occurred between the pair of filaments. Two faces of the filaments have completely fused together along a width greater than the radius of a circle circumscribed about a single filament. Interrupted fusion is shown between another pair of filaments 64, 65. The line 66 has been drawn to show where fusion occurred between two lobes at 67 and between two lobes at 68 to leave an intermediate void 69. An attenuated form of interfilament fusion is shown between still another pair of filaments 71 and 72. The numerous specks 70 observed in the filament cross sections are particles of delusterant (TiO and other insoluble materials incorporated in the polymer prior to spinning, which have nothing to do with the present invention.

FIGURE 7 is an enlarged side view of a portion of a yarn of this invention. This shows the bulky nature of the yarn, but the filaments must be separated to see the interfilament fusions. FIGURE 8 shows a pair of filaments on a larger scale. Interfilament fusion has occurred at portion 71 and at portion 72 along the filaments. The filaments have a random three-dimensional, non-helical, curvilinear, extensible configuration.

The following examples illustrate embodiments of the invention but are not intended to be limitative:

EXAMPLE 1 (a) Continuous filament polyester yarn is drawn and crimped by the procedure illustrated in FIGURE 1. The supply yarn is 270 denier, 50 filament, zero twist, undrawn yarn of filaments having a trilobal cross section (of the type illustrated in FIGURE 6) and coated with approximately 0.05% by weight of a neutral textile finish agent composed primarily of polyalkylene oxide condensation products. The polyester is polyethylene terephthalate/S-(sodium sulfo)isophthalate (98/2) having a relative viscosity of 19.5 and containing 0.45% by Weight of TiO The yarn is drawn 3.4x through steam at 47 p.s.i.g. and 175 C. and is then passed 6 /2 wraps around a pair of rolls maintained at a temperature of 165 C. The drawn denier is 83. The yarn is passed from these rolls at 2000 yards per minute (y.p.m.) into a fluid jet device of the type shown in FIGURE 2. The yarn treatment chamber is 4 inches long and has a crosssectional area of about 0.0054 square inch.. The fluid passage into the chamber has a cross-sectional area of 0.002 sq. in. Air is supplied at 300 C. and 67 p.s.i.g. to provide a turbulent plasticizing stream in the chamber for crimping the filaments. The yarn is forwarded by the air stream to a screen-surfaced drum, 9 inches in diameter, spaced 0.06 inch from the exit orifice of the jet device. The drum rotates at a peripheral speed of 71 y.p.m. and carries the yarn away from the hot air fiutfy, voluminous yarn bundle.

a 200 rotation of the drum away from the jet orifice,

and is Wound up at 1328 y.p.m.

The yarn produced by the above procedure has a denier of 124 (as contrasted with before the bulking treatment), a yield elongation of 5.3% and a breaking load of 174 grams. Photomicrographs made of 12 transverse cross sections, taken at random along the yarn, show an average of 1.3 interfilament fusions per filaments in these cross sections. Examination of the individual filaments shows that the fusions 'are widely separated at random intervals along their lengths, and that the filaments are crimped in a random, three-dimensional, non-helical, curvilinear, extensible configuration which is random from filament to filament across the yarn bundle.

The yarn bundle is well defined and has excellent coherence. A 1 x 1 plain weave fabric prepared from the yarn, having 80 ends per inch in the warp and 70 ends per inch in the filling, has a weave pattern of excellent uniformity and a pleasing, dry, cotton-like hand.

(b) For comparison, the procedure of 1(a) is modified by using a supply yarn having a coating of 0.09% finish containing 1% by weight sodium hydroxide, drawing the yarn through 80 p.s.i.g. steam at 190 C. to 84 denier, passing the yarn at 2750 y.p.m. into the jet device supplied with 60 p.s.i.g. air at 278 C., and winding up the crimped yarn at 1900 y.p.m. The bulked yarn has a denier of 121 (as contrasted with 84 before the bulking treatment), a yield elongation of 4.0% and a breaking load of grams. Photomicrographs of 20 transverse cross section-s, taken at random along the yarn, show no evidence of interfilament fusion. The filaments are crimped in a random, three-dimensional, non-helical, curvilinear, extensible configuration which provides a However, processing of this yarn into fabric is impractical until it is twisted, and the introduction of twist is an undesirable, relatively slow process. A 1 x 1 plain weave fabric prepared from the yarn has a very soft hand, quite unlike the fabric of (a) Example 1(a). is repeated except that the' yarn is drawn 3.0x through 80 p.s.i.g. steaem at C. to 90 denier, is passed at 2750 y.p.m. into a jet device of the type shown in FIGURE 3 supplied with 60 p.s.i.g. air at 300 C., the screen-surfaced drum rotates at a peripheral speed of 141 y.p.m. and the yarn is wound up at 1861 y.p.m. The dimensions of the yarn treatment chamber of the jet device, and of the fiuid passages into the chamber, are the same as those given in Example 1(a). The bulked yarn has a denier of 133, a yield elongation of 5.9% and a breaking load of 161 grams. Photomicrographs of 12 transverse cross sections, taken at random along the yarn, show an average of about 8 interfilament fusions per 100 filaments in these cross sections. The fusions are widely separated at random intervals along individual filaments, and the filaments are crimped in a random, three-dimensional, non-helical, curvilinear, extensible configuration which is random from filament to filament across the yarn bundle. The yarn bundle is well defined and has excellent coherence. A 1 x 1 plain weave fabric prepared from the yarn, having 80 ends per inch in the warp and 70 ends per inch in the filling, has a weave pattern of excellent uniformity and a dry, cotton-like hand.

(b) For comparison, procedure 2(a) is modified by 7 prepared from this yarn has a non-uniform weave pat tern and a harsh, unpleasant hand.

EXAMPLE 3 Continuous filament 66-nylon yarn is processed by a similar procedure, but using a jet device of the type shown in FIGURE 4 supplied with 105 p.s.i.g. steam at increasing temperatures. The yarn treatment chamber is 0.099 inch in diameter (0.0077 sq. in. cross section) and about 2 inches long. Zero twist, 2300 denier yarn of 158 filaments having a trilobal cross section is introduced into the treatment chamber through the needle-like passage at 50 y.p.m. and is wound up after treatment at 36.5 y.p.m. (37% overfeed). The bulk increases as the steam temperature is increased to 450 F. (232 C.). When treated at this temperature the individual filaments have 10 to 15 crimps per inch in a random, three-dimensional, non-helical, curvilinear, extensible configuration. Above this temperature the bulk becomes less as the crimps become smaller and more frequent until fusion takes place above about 560 F. (293 C.) under the conditions given in this example.

EXAMPLE 4 A 2100 denier 6-nylon yarn having 112 filaments and Zero twist is passed through the jet shown in FIGURE 4. The machine overfeed is 100% and the feed speed is 200 y.p.m. Three different processing temperatures are studied: 375 F. (191 C.), 435 F. (224 C.), and 515 F. (268 C.). The yarn processed at 375 F. has only moderate bulk. The yarn processed at 435 F. has high bulk. The yarn processed at 515 F. has a high bulk and is coherent as in Example 1(a). Using this jet and this feed speed, it is not possible to process the 6- nylon yarn at temperatures as high as 550 F. (288 C.) without melting the yarn. The properties of the bulked yarn are shown in Table I.

Table I STEAM BULKED YARNS FROM G-NYLON (AFTER TEN- SIONING AND RELAXED BOIL-OFF) A 66-nylon tow of 80,000 denier and 20,000 filaments is fed at 2 y.p.m. to a jet device of the type illustrated in FIGURE 5 having a yarn treatment chamber in the form of a slot 4 inches wide. The tow is fed to the jet device in a flattened ribbon form so that all parts of the yarn opening and treatment chamber are filled in a substantially uniform fashion. The turbulent fluid is 70 p.s.i.g. steam, heated to 550 F. (288 C.). The bulked tow has a relaxed denier of about 150,000. The individual filaments have an average crimp elongation of 86% and an average of 22 crimps per inch in a random, threedimensional, non-helical, curvilinear, extensible configuration. In relaxed form, this product has a specific volume (bulk) of 70 cubic centimeters per gram. It shows a fabric-like cohesiveness in both lengthwise and widthwise directions.

EXAMPLE 6 (a) Continuous filament polyester yarn is drawn and crimped in general accordance with the procedure of Example 1(a). The steam temperature and pressure in the drawing step are 176 C. and 50 p.s.i.g.; the draw ratio is 3.67 and the drawn denier is 80. The dimensions of the yarn treatment chamber of the jet device,

and of the fluid passages into the chamber, are the same as those given in Example 1(a); however, the temperature and pressure of the air supplied to the jet device are reduced to 275 C. and 43 p.s.i.g., respectively. The yarn is passed into the jet device at 2045 y.p.m. and the screen-surfaced drum rotates at a peripheral speed of 93 y.p.m. The yarn is removed from the drum after a 205 rotation of the drum away from the jet orifice and is wound up at 1303 y.p.m.

The yarn produced by the above procedure has a denier of 125.5 (as contrasted with before the bulking treatment), a yield elongation of 6.9%, and a breaking load of 175 grams. The frequency of interfilament fusions, as determined by photomicrographs taken at random along the yarn, averages about 0.5 fusion per filaments. Attenuated interfilament fusions of the type shown between filaments 71 and 72 in FIGURE 6 are present in this yarn. The filaments are crimped in a random, three-dimensional, non-helical, curvilinear, extensible configuration which is random from filament to filament across the yarn bundle. The yarn bundle is well defined and has excellent coherence. A 1 x 1 plain Weave fabric prepared from the yarn and having 80 ends per inch in the warp and 70 ends per inch in the filling has a weave pattern of excellent uniformity and a soft, desirable hand.

(b) In a modification of the above experiment, a jet device is employed in which the cross-sectional area of the yarn treatment chamber is 0.0105 square inch instead of 0.0054 square inch and the fluid passage into the chamber has a cross sectional area of 0.004 square inch instead of 0.002 square inch. The steam temperature and pressure in the drawing step are C. and 50 p.s.i.g.; the draw ratio is 3.45 X and the drawn denier is 85. The drawn yarn is passed at 2045 y.p.m. into the jet device, which is supplied with air at a temperature of 280 C. and a pressure of 34 p.s.i.g. The drum is rotated at a peripheral speed of 94 y.p.m. The yarn is removed from it after a rotation away from the jet orifice and is wound up at 1383 y.p.m.

The yarn so produced has a denier of 125.5 (as contrasted with 85 before the bulking treatment), a yield elongation of 6.2%, and a breaking load of 191 grams. Examination of photomicrographs of lingitudinal and transverse cross sections of the yarn reveal interfilament fusions, all of which are of the attenuated type shown between filaments 71 and 72 in FIGURE 6. The filaments are crimped in a random, three-dimensional, nonhelical, curvilinear, extensible configuration which is random from filament to filament across the yarn bundle. The yarn bundle is well define dand has excellent coherence, but is also highly flexible. A 1 x 1 plain Weave fabric prepared from the yarn and having 80 ends per inch in the warp and 70 ends per inch in the filling has a weave pattern of excellent uniformity and a desirable hand.

Since many dilferent embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

We claim:

1. In the process for imparting crimp to a multilament strand of plasticizable synthetic linear polymer filaments by feeding the strand through a turbulent plasticizing stream of a compressible fluid having a temperature of at least 150 C. in which the individual filaments, while in a plastic state and under substantially zero tension, are separated from each other and crimped into a random, three-dimensional, curvilinear, extensible configuration, then setting the crimp and taking up the strand at a rate which provides at least 30% overfeed to the turbulent stream; the method of producing a coherent bulky filament bundle which comprises maintaining the compressible fluid in said turbulent stream at a temperature above the melting point of said polymer filaments and feeding the strand through the turbulent stream of compressible fluid at a temperature greater than the interfilament stick temperature of the filaments to cause fusion between filaments during the crimping treatment.

2. The process defined in claim 1 wherein the temperature of the filament surfaces in the turbulent fluid is above the melting point of the filaments and the strand is fed through the fluid at a speed providing interfilament fusions visible in cross sections which average 0.1 to 10 interfilament fusions per 100 filaments, as determined at random cross sections along the strand.

3. A multifilament strand of synthetic linear polymer References Cited by the Examiner UNITED STATES PATENTS 2,369,395 2/1945 Heymann 2872 10 2,815,559 12/1957 Robinson 5734 3,055,080 9/1962 Claussen et al 28-1 3,058,291 10/1962 Heberlein et al. 57140 5 3,061,998 11/1962 Bloch 57--140 FOREIGN PATENTS 636,054 2/ 1962 Canada.

References Cited by the Applicant 10 UNITED STATES PATENTS 2,079,133 5/1937 Taylor. 3,110,617 11/1963 Scott.

15 FOREIGN PATENTS 861,108 2/1961 Great Britain. 905,895 9/1962 Great Britain.

20 MERVIN STEIN, Primary Examiner. 

3. A MULTIFILAMENT STRAND OF SYNTHETIC LINEAR POLYMER FILAMENTS CRIMPED IN A RANDOM, THREE-DIMENSIONAL, NONHELICAL, CURVILINEAR, EXTENSIBLE CONFIGURATION, AND HAVING AN AVERAGE OF 0.1 TO 10 INTERFILAMENT FUSIONS PER 100 FILAMENTS, AS DETERMINED AT RANDOM CROSS SECTIONS ALONG THE STRAND, TO PROVIDE A COHERENT BULKY FILAMENT BUNDLE. 